Wind power installations with an adjusting device for the blade have long been known in the state of the art and are also described in the specialist literature. Thus for example in the work by Erich Hau in ‘Windkraftanlagen’, [‘Wind power installations’], Springer-Verlag, 2nd edition, 1996, pages 231 ff.
That adjusting device must be designed in such a way that it can put the rotor blade or, in the case of central rotor blade adjustment, the rotor blades, into a predeterminable position in an acceptable time. For that purpose, a drive motor is frequently provided in the state of the art, and that motor must have a minimum power output which is predetermined by the rotor blades and the loads thereof.
Irrespective of considerations relating to the use and the design of transmission arrangements, it has been determined by the inventor that, with an increasing size of installation, the rotor blades also become larger and therefore the drive motor used for rotor blade adjustment must also furnish a higher power output. That higher power output inevitably results in the drive motor being of larger dimensions.